On 14/07/10 15:51, Aaron Riemer wrote:
Yes i have read all about unicast flooding:
Can occur by:
1) Asymmetric routing
2) Spanning Tree TCN
3) MAC aging out
I cannot see any TCN's or Asymmetric routing so i think we may have to
adjust the mac aging as you suggested.
If you're running HSRP, the standby node has a route for the subnet as
well as the active e.g. traffic might flow out through the active, and
back through the standby as follows:
host
|
active-standby
| |
(cloud) ^
| |
router --/
|
target
from host->active->router-target
return target->router->standby->host
...if "standby" has an ARP entry (default 4 hours) but not MAC table
entry (default 5 minutes) it will unknown-unicast-flood the return
traffic. If it's a lot of traffic, that will burn a lot of bandwidth...
Whether this will happen will depend on your routing topology.
I am just trying to work out why the hell this has only just started
occurring!
Well, without knowing the source of the traffic it's impossible to tell.
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